DE112017004872T5 - Dielectric elastomeric material, and transducer, for which it is used - Google Patents

Abstract

A dielectric elastomeric material contains a copolymer having a structure for which at least one of a monomer A and a monomer C having a crosslinkable functional group and a monomer B having a polar group has been randomly or alternately copolymerized. In this copolymer, the polar group in the constituent units consisting of the monomer B is coupled to the polymer main chain via at least three straight-chain connected atoms. A transducer (1) comprises a dielectric layer (10) of the dielectric polymer material and a plurality of electrodes (11a, 11b) interposed therebetween with the dielectric layer (10).

Description

Technical area

The present invention relates to a dielectric elastomeric material that is ideal for, for example, the dielectric layer of a transducer or the like.

General state of the art

As transducers, there are known actuators, sensors, power generating elements, or the like which make a conversion between mechanical energy and electric power, or speakers, microphones, or the like which make a conversion between sound energy and electric power. To form small-sized and lightweight transducers with high elasticity, high molecular weight materials such as dielectric elastomers are useful.

For example, an electrostrictive type actuator may be formed by arranging a pair of electrodes on both surfaces in the thickness direction of a dielectric elastomer dielectric layer. This type of actuator drives a driven element by expanding and contracting the dielectric layer by the magnitude of a voltage applied between the electrodes. The force developed and the amount of displacement of the actuator are determined by the magnitude of the applied voltage and the electrostatic attraction between the electrodes. That is, the larger the applied voltage and the larger the electrostatic attraction generated between the electrodes, the larger the developed force and the amount of displacement of the actuator become.

In the same way, a sensor and a current-generating element may be formed by arranging a pair of electrodes on both surfaces in the thickness direction of a dielectric elastomer dielectric layer. In the sensor and the power generating element, an electromotive force is generated by the dielectric layer expanding and contracting. The amount of electromotive force generation is in proportion to the amount of displacement of the distance between the electrodes and the relative dielectric constant of the dielectric layer. That is, the larger the amount of shift of the distance between the electrodes and the larger the relative dielectric constant of the dielectric layer, the larger the electromotive force becomes.

For example, silicone rubber has excellent dielectric breakdown resistance, but the relative dielectric constant is low. Therefore, when the silicone rubber dielectric layer is formed, the electrostatic attraction with respect to the applied voltage is small, and the developed force and the amount of displacement desired by an actuator are hard to obtain. Even with a sensor and a power generating element, the desired electromotive force is difficult to obtain. In the case of acrylic rubber and nitrile rubber, although the relative dielectric constant is high compared with silicone rubber, it can not yet be said to be sufficient. Therefore, attempts are made to increase the relative dielectric constant of the dielectric layer by introducing polar groups into an elastomer constituting the base material or scattering particles having a large relative dielectric constant therein.

For example, in Patent Literature Example 1, there is described an artificial muscle containing an elastic thin film of an electrostrictive polymer having polar groups in side chains of silicone rubber or the like, and elastic electrodes. In Patent Literature Example 2, a polymer material is described wherein a copolymer of (meth) acrylic acid ester, (meth) acrylic acid, an ionic liquid, and acrylonitrile has been crosslinked. In Patent Literature Example 3, there is described a dielectric for a high-molecular actuator of a block copolymer (A) comprising a polymer block ( B1 ) of methacrylic acid and a polymer block ( B2 ) of alkyl acrylate. In paragraph [0040] of Patent Literature Example 3, a form is described in which the polymer blocks ( B1 ) B2 ) with the intention to increase the relative dielectric constant, containing as an additional constituent monomers with polar groups. In Patent Literature Example 4, a dielectric film made of an elastomer to which a polar compound is graft-coupled is described. In Patent Literature Example 5, a dielectric film made of an elastomer in which nanoparticles having cyano groups are dispersed is described.

Literature of the precursor technique

patent literature

• Patent Literature Example 1: Patent Publication 2008-199784
• Patent Literature Example 2: Patent Publication 2015-67662
• Patent Literature Example 3: International Publication 2009/025187
• Patent Literature Example 4: Patent Publication No. 2011-072112
• Patent Literature Example 5: Patent Publication 2015-187931

Brief description of the invention

Task to solve the invention

(F: entwickelte Kraft; ε₀: Dielektrizitätskonstante im Vakuum; ε_r: relative Dielektrizitätskonstante der dielektrischen Schicht; V: angelegte Spannung; d: Dicke der dielektrischen Schicht)When polar groups are incorporated into an elastomer, the polarity of the elastomer becomes high and the relative dielectric constant becomes large. In this case, the developed force obtained upon application of a voltage becomes large according to the following formula (i). Therefore, investigations have heretofore been made from the viewpoint of how many polar groups can be introduced to make the relative dielectric constant of the dielectric layer large. $$\text{F}={\mathrm{\epsilon }}_0{\mathrm{\epsilon }}_{\text{r}}\times {\left(\text{V / d}\right)}^2$$

(F: developed force; ε ₀ : dielectric constant in vacuum; ε _r: relative dielectric constant of the dielectric layer; V: applied voltage; d: thickness of the dielectric layer)

However, the inventors of the present invention have come to the realization by repeated eager research that only by increasing the amount of polar groups in the elastomer, only the modulus of elasticity becomes large, but sufficient effect of increasing the relative dielectric constant can not be obtained. The reason for this is considered that as the amount of the polar groups increases, the polar groups interfere with each other or the polar groups and the elastomeric chain and agglutinate the polar groups by the interaction. For example, acrylonitrile has a polar group (cyano group: -CN). But polyacrylonitrile, for which it has been polymerized, is hard, and its relative dielectric constant is not high at about 4. In the polymer material described in Patent Literature Example 2, acrylonitrile is copolymerized. However, it can not be said that only thereby does a sufficient effect of increasing the relative dielectric constant exist. In paragraph [0028] of this patent literature example, it is described that the elastic modulus becomes large when the contained amount of acrylonitrile 45 Exceeds percent by mass.

The present invention has been made in view of these circumstances and has an object to provide a soft dielectric elastomer material having a large relative dielectric constant. It is also intended to provide a soft transducer for which this dielectric elastomeric material is used.

Means of solving the task

(1) The dielectric elastomeric material of the present invention is characterized by being a copolymer having a constitution of which at least one of a monomer A and a monomer C having a crosslinkable functional group and a monomer B having a polar group , randomly or alternately copolymerized, wherein in the copolymer the polar group in the constituent units consisting of the monomer B is coupled to the polymer main chain via at least three straight-chain connected atoms.

The copolymer constituting the dielectric elastomeric material of the present invention contains constituent units of the monomer B containing a polar group. The polar group is a functional group with high polarity. In the constituent units of the monomer B, the polar group is coupled to the polymer main chain via at least three straight-chain connected atoms. In other words, there are at least three straight-chain atoms between the polar groups and the main polymer chain. By removing the polar groups and the polymer backbone from each other, the polar groups hardly interfere with the main polymer chain and scarcely restrict the movement of the polar groups through the polymer chain. This makes the polar groups easily mobile and can increase the softness of the copolymer, and hence of the dielectric elastomeric material. In addition, since the peculiarity of the polar groups that the polarity is high is brought about in full, the relative dielectric constant of the copolymer, and hence the dielectric elastomeric material, can be increased.

The copolymer constituting the dielectric elastomeric material of the present invention has the constitution of a random copolymer or an alternating copolymer based on at least one of the monomer A and the monomer C, and the monomer B. The constituent units of the copolymer are any of A-B, B-C and A-B-C (the arrangement order of the repeating units is not limited). Since the constituent constituent units are randomly or alternately coupled, constituent units of the monomer B having the polar group hardly follow each other as compared with the structure of a block copolymer. That is to say, constituent units of the monomer B having the polar group are scarcely adjacent to each other. This suppresses interference between the polar groups and makes the polar groups easily mobile. Consequently, the softness of the copolymer, and hence the dielectric elastomeric material, can be increased. In addition, since the peculiarity of the polar groups that the polarity is high is brought about in full, the relative dielectric constant of the copolymer, and hence the dielectric elastomeric material, can be increased.

In the patent literature example 3 is a block copolymer described. As described in paragraphs [0056] to [0060] of this literature example, the block copolymer (A) is prepared by following the preparation of the first polymer block ( B1 ) the second polymer block ( B2 ) and with the first polymer block ( B1 ) is coupled. In the polymer blocks produced ( B1 ) B2 ) same monomers follow each other. Therefore, when the polymer blocks are prepared by adding monomers having polar groups, the polar groups interfere with each other and the effect of increasing the relative dielectric constant is small.

(2) The converter of the present invention is characterized by comprising a dielectric layer of the above-described dielectric elastomer material of the present invention, and a plurality of electrodes interposed therebetween with the dielectric layer.

As described above, the relative dielectric constant of the dielectric elastomer material of the present invention is high. Therefore, in the dielectric layer of the transducer of the present invention, the static attraction with respect to the applied voltage is large. In addition, the dielectric elastomer material of the present invention is soft. Therefore, in the converter of the present invention, even in the case of a relatively small applied voltage, a large force and a large amount of displacement can be obtained.

list of figures

• 1 Fig. 12 is a sectional schematic view of an actuator which is an embodiment of the transducer of the present invention.
• 2 Fig. 10 is a front front view of an actuator attached to a measuring device.
• 3 is a sectional view taken along III-III in FIG 2 ,
• 4 Figure 11 is a plan view of an actuator for measuring the amount of displacement.
• 5 is a sectional view taken along VV in FIG 4 ,

Explanation of the reference numbers

• 1: actuator (transducer); 10: dielectric layer; 11a, 11b: electrode; 12a, 12b: Wiring
• 5: actuator; 50: dielectric layer; 51a, 51b: electrode; 52: upper chuck; 53: lower clamping device
• 6: actuator; 60: dielectric layer; 61a, 61b: electrode; 62: power source; 63: displacement meter; 610a, 610b: terminal portion; 630: marking

Embodiments of the invention

Embodiments for the dielectric elastomeric material and the transducer of the present invention will be explained below. However, the dielectric elastomeric material and the transducer of the present invention are not limited to the following forms; Within a scope that does not depart from the gist of the present invention, various forms may be made to which any person skilled in the art can make changes, improvements, etc.

The dielectric elastomeric material

The dielectric elastomeric material of the present invention contains a copolymer having a structure for which at least one of a monomer A and a monomer C having a crosslinkable functional group and a monomer B having a polar group has been randomly or alternately copolymerized.

The monomer A

For the monomer A, there are no significant restrictions. When the dielectric elastomeric material of the present invention is used as a dielectric layer of a transducer, it is advisable to choose a monomer having a comparatively large relative dielectric constant which can provide softness. In addition, the choice of a monomer which is copolymerizable with the monomer B and whose glass transition point (Tg) as a copolymer reaches at most the normal temperature (20 ° C) is advisable. For example, monomers used for isoprene rubber, butadiene rubber, ethylene-propylene rubber, nitrile rubber, chloroprene rubber, butyl rubber, chlorosulfonated polyethylene rubber, fluororubber, thermoplastic elastomers, acrylic rubber, silicone rubber and urethane rubber can be given. Among the above, monomers used from the viewpoint of easy copolymerizability with the monomer B for acrylic rubber, silicone rubber and urethane rubber, that is, (meth) acrylate monomers, silicone monomers and urethane monomers are ideal. The monomer A may be one kind but may also be two or more species.

The term "(meth) acrylic monomers" means that it includes both acrylates and methacrylates. "(Meth) acrylate monomers" means monomers containing (meth) acryloyl groups. The term "(meth) acryloyl groups" means that it includes both acryloyl groups and methacryloyl groups. As (meth) acrylate monomers are alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate; Hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, dodecyl (meth) acrylate, tetradecyl (meth) acrylate, hexadecyl (meth) acrylate, Octadecyl (meth) acrylate, or the like.

When an alkyl (meth) acrylate is used, it is desirable that the carbon number of the alkyl group is at least 1 and at most 12. Even more ideally, it is at most 8. As the carbon number increases, the alkyl group becomes longer and larger. In this case, there is a fear that interference of the polar group of the monomer B with the alkyl group of the monomer A is likely to occur and the effect of increasing the relative dielectric constant becomes small. In addition, as the alkyl group becomes longer, crystallinity increases and softness decreases.

Silicone monomers mean monomers for which siloxane bonding is possible. As silicone monomers, diethoxydimethylsilane having a bifunctional alkoxy group, diethoxymethylsilane, diethoxymethylvinylsilane, dimethoxydimethylsilane, dimethoxy (methyl) silane, dimethoxymethylvinylsilane, or the like are ideal. Urethane monomers are monomers where urethane bonding is possible.

The monomer B

The monomer B has a polar group. It is advisable that the polar group is a functional group of bonds that has a high dipole moment that interacts with the relative dielectric constant. Concretely, there may be mentioned, for example, a cyano group, an ether group, an ester group, a fluoro group, a trifluoromethyl group, a carbonate group, or the like, which are already known high-polar groups.

In the copolymer, the polar groups in the constituent units of the monomer B are coupled to the polymer main chain via at least three rectilinear connected atoms. From the point of view In terms of softness and polymerization control, the number of atoms present in a line between the polar group and the polymer backbone is more preferably at least four. When the number of polar groups is a plural number, the number of atoms between the polar group closest to the polymer main chain and the main polymer chain is counted. It is preferable that the atoms existing in a row between the polar group and the polymer main chain are at least one kind of carbon (C), oxygen (O), nitrogen (N) and sulfur (S) , For example, for the skeleton of the monomer B other than the polar group, acrylic (meth) acrylate having a carbon number of the alkyl group of at least 2, silane having a bifunctional alkoxy group and an alkyl group having a carbon number of at least 2, or the like can be given.

To summarize the above, for the monomer B, cyanomethyl (meth) acrylate (number of atoms between the polymer main chain and the cyano group: 3), cyanoethyl (meth) acrylate (number of atoms between the polymer main chain and the cyano group: 4), cyanopropyl ( meth) acrylate (number of atoms between the polymer main chain and the cyano group: 5), cyanobutyl (meth) acrylate (number of atoms between the polymer main chain and the cyano group: 6), or the like. In addition, cyano group-modified silane for which dimethoxy-3-mercaptopropylmethylsilane was reacted with acrylonitrile (number of atoms between the polymer main chain and the cyano group: 6), cyano group-modified silane, for which dimethoxy-3-mercaptopropylmethylsilane was reacted with 2-methyleneglutaronitrile (number of atoms between the Polymer backbone and cyano group: 6), and the like are ideal. Of those named, one species may be used alone, but two or more species may be shared.

As the amount of polar groups contained becomes high, the softness of the copolymer decreases. However, if there are too few polar groups, no effect for increasing the relative dielectric constant is obtained. For this reason, it is advisable that the amount of polar group contained when the total copolymer is used as 100% by mass is at least 10% by mass, and ideally at least 12% by mass. In addition, it is advisable that the amount of polar group contained when the total copolymer is used as 100% by mass is at most 25% by mass, and ideally at most 22% by mass. For the same reason, it is advisable that the amount of the monomer B contained when the total copolymer is used as 100 mol% is at least 50 mol%, and ideally at least 60 mol%. In addition, it is advisable that the amount of the monomer B contained when the total copolymer is used as 100 mol% is at most 98 mol%, and ideally at most 90 mol%.

The monomer C

The monomer C has a crosslinkable functional group (crosslinking group) and serves the role of crosslinking the copolymer. As the crosslinkable functional group, a hydroxy group, an amino group, a thiol group, a carboxyl group, a silanol group, an epoxy group, a vinyl group, or the like can be given. When the dielectric elastomer material of the present invention is used as a dielectric layer of a transducer, it is advisable to choose as monomer C a monomer having a relatively large relative dielectric constant. For example, (meth) acrylic acid, (meth) acrylic acid hydroxyethyl, (meth) acrylamide, (meth) acrylic acid glycidyl, 3-aminopropyldimethoxymethylsilane, dimethoxymethylvinylsilane, 3-glycidyloxipropyl (dimethoxy) methylsilane, 3-mercaptopropyl (dimethoxy) methylsilane, 3-aminopropyldiethoxymethylsilane, diethoxy ( 3-glycidyloxypropyl) methylsilane, diethoxymethylvinylsilane, or the like.

The copolymer

The copolymer constituting the dielectric elastomeric material of the present invention has the constitution of a random copolymer or an alternating copolymer of at least one of the monomer A and the monomer C, and the monomer B. There are no significant limitations to the process for making the copolymer. For example, any one of a random copolymer or an alternating copolymer of the monomer A and the monomer B, a random copolymer or an alternating copolymer of the monomer B and the monomer C, and a random copolymer or an alternating copolymer of the monomer A, the monomer B and the monomer C. Moreover, after random or alternating copolymerization, at least one of the monomer A and the monomer C, and a precursor of the monomer B (a monomer B 'having no polar group), it is possible to form a monomer having a polar group with the constituent units of the group Monomers B 'to react and synthesis units of the monomer B, which has a polar group to synthesize. That is, it is possible to prepare a copolymer of at least one of the monomer A and the monomer C, and the monomer B 'by a modification treatment to give the monomer B 'a polar group. For example, in the case of imparting a cyano group, a cyano group-containing monomer such as acrylonitrile, 2-methyleneglutaronitrile, tetracyanoethylene, or the like can be used.

From the viewpoint of ensuring softness, it is favorable that the weight-average molecular weight of the copolymer is at least 10,000. Even more ideally, it is at least 50,000 and especially at least 80,000. On the other hand, from the viewpoint of uniform solubility with respect to the required solvent required in the film production, it is favorable if it is at most 5,000,000, with at most 2,000,000 being even more ideal. The weight-average molecular weight can be measured by using a gel permeation chromatography (GPC) apparatus.

The glass transition point (Tg) of the copolymer is at most the normal temperature (20 ° C), and from the viewpoint of ensuring softness, at most 5 ° C are favorable. Even better, it is at most 0 ° C. The glass transition point can be measured using a differential scanning calorimeter (DSC).

It is favorable if the relative dielectric constant of the copolymer is at least 10. In the present specification, the relative dielectric constant is measured by placing a sample of the copolymer on a sample holder (Model 12962A from Solartron) and simultaneously using a dielectric interface (model 1296 of the same company) and a frequency response analyzer (model 1255B of the same company) (measurement frequency 100) Hz).

It is advisable that the copolymer has a crosslinked structure, that is, a crosslinked body. If it has a crosslinked structure, the elastic modulus becomes large and the mechanical strength becomes large. In addition, the dielectric breakdown strength also becomes large. In order to crosslink the copolymer, a well-known crosslinking agent, crosslinking accelerator, crosslinking assistant or the like corresponding to the crosslinking group of the monomer C may be used. For example, when sulfur is used, a reaction residue of unreacted sulfur, a vulcanization accelerator, decomposition products thereof, or the like often occurs in the copolymer after crosslinking. The reaction residue ionizes and becomes the cause of a decrease in the dielectric breakdown strength of the copolymer, and hence the dielectric elastomeric material. Consequently, for the reason of reducing the ion component in the copolymer, it is advisable to use as the crosslinking agent an organometallic compound or an isocyanate compound. When an organometallic compound is used, the metal oxide particles formed from the organometallic compound are scattered in the copolymer. Therefore, the dielectric strength of the copolymer can be further increased. For the organometallic compound, metal alkoxide compounds, metal acylate compounds and metal chelate compounds can be cited. There may be used a single kind selected thereof, but two or more kinds may be shared. It is desirable that the organometallic compound contain at least one element selected from titanium, zirconium, aluminum, silicon, boron, hafnium, manganese, iron, cobalt, germanium, yttrium, niobium, lanthanum, cerium, tantalum, tungsten and magnesium.

The dielectric elastomeric material of the present invention may contain other ingredients in addition to the copolymer. For example, when an insulating filler having electrical insulating ability is picked up, the dielectric strength of the dielectric elastomeric material becomes large. For the insulating filler, inorganic particles having a volume resistivity of at least 10 ⁸ Ω · cm are ideal. For example, particles of titania, silica, zirconia, barium titanate, calcium carbonate, clay, calcined clay, talc, or the like. For the insulating filler, one kind may be used alone, but two or more kinds may be used together.

When a piezoelectric filler is picked up, the dielectric elastomeric material of the present invention can be used as a piezoelectric layer of a transducer element having a piezoelectric function. As the piezoelectric filler, a compound having piezoelectric properties can be used. For the compound having piezoelectric properties, there is no limitation to organic substances or inorganic substances, and for example, a strong dielectric having a perovskite-type crystal structure is advisable. For example, barium titanate, strontium titanate, potassium niobate, sodium niobate, lithium niobate, potassium sodium niobate, lead zirconate titanate (PZT), barium strontium titanate (BST), bismuth lanthanum titanate (BLT), strontium bismuth tantalate (SBT), or the like may be cited. For the piezoelectric filler, one kind may be used alone, but two or more kinds may be used together.

The method of making the dielectric elastomeric material

The dielectric elastomeric material of the present invention can be prepared by randomly or alternately copolymerizing at least one of the monomer A and the monomer C, and the monomer B. Or, it may be prepared by subjecting, after random or alternating copolymerization, at least one of the monomer A and the monomer C, and a precursor of the monomer B (a monomer B 'having no polar group) to a monomer having a polar group Assembly units of the monomer B 'is reacted. In this case, a crosslinking agent or the like may be added to the obtained copolymer, and the copolymer may be crosslinked. It is also possible to mix it with other monomers in a non-functional extent. In addition, other ingredients such as an insulating filler, a piezoelectric filler, a plasticizer, a processing aid, an aging inhibitor, a plasticizer, a coloring agent, or the like may be blended into the obtained copolymer.

The converter

The converter of the present invention comprises a dielectric layer of the above dielectric elastomeric material of the present invention and a plurality of electrodes interposed therebetween with the dielectric layer.

From the viewpoints of ensuring film-forming accuracy and reducing errors, it is advisable that the thickness of the dielectric layer be at least 5 μm. On the other hand, if the thickness of the dielectric layer becomes too large, a large voltage is required for the drive and the cost becomes high. Therefore, it is advisable that the thickness of the dielectric layer is 200 μm or less.

It is advisable that the multiple electrodes of the dielectric layer are subsequently deformable. Such an electrode may be formed using a binder and a conductive material. From the viewpoint of such formation of the electrode that the electric resistance is difficult to increase even when expanding and contracting, an elastomer is ideal as a binder. As the elastomer, a crosslinked rubber such as nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), ethylene-propylene-diene copolymer (EPDM), silicone rubber, natural rubber, styrene-butadiene rubber (SBR), acrylic rubber, urethane rubber, epichlorohydrin rubber, chlorosulfonated polystyrene, chlorinated polyethylene, or the like, and a styrene-based, olefin-based, PVC-based, polyester-based, polyurethane-based, polyamide-based, or the like thermoplastic elastomer may be mentioned. Or, an elastomer modified by incorporation of a functional group or the like, such as epoxy-modified acrylic rubber, carboxyl group-modified hydrogenated nitrile rubber, or the like may also be used.

There are no significant restrictions on the type of conductive material. It may be suitably selected from conductive carbon powder such as carbon black, carbon nanotubes, graphite, graphene or the like, metal powders of silver, gold, copper, nickel, rhodium, palladium, chromium, titanium, platinum, iron and alloys thereof, or the like, etc. , It is also possible to use a powder of metal-coated particles such as silver-coated copper powder or the like. Also, a conductive polymer having a structure associated with π-electrons may be used. It is possible to use only one kind of the same, but two or more kinds may be shared.

The electrodes may contain addition agents such as a dispersant, a plasticizer, an anti-aging agent, a coloring agent, or the like, in addition to the binder and the conductive material, as necessary. For example, when an elastomer is used as a binder, a conductive coating material can be prepared by adding a polymer solution for which the polymer of the elastomer portion has been dissolved by a solvent, adding the conductive material and adding agents as necessary, and mixing and mixing. An electrode may be formed by directly applying the prepared conductive deposition material to a surface of the dielectric layer. Or, it is possible to form the electrode by applying the conductive coating material to a release film, and to transfer the formed electrode to a surface of the dielectric layer.

When the converter of the present invention is embodied as a multilayered structure in which a plurality of dielectric layers and electrodes are alternately stacked, an even larger force can be generated. In the transducer of the present invention, a protective layer may also be disposed on the outermost layer. By arranging the protective layer, the insulating ability can be ensured and the transducer can be protected from mechanical stresses from the outside. It is advisable that the protective layer is soft and has elasticity. It is preferable that the protective layer be formed to contain, for example, urethane rubber, silicone rubber, NBR, H-NBR, ethylene-propylene copolymer rubber, EPDM, natural rubber, styrene-butadiene rubber, acrylic rubber, or the like. In addition, in the transducer of the present invention, the dielectric layer can also be constructed by stacking the same or different layers. In addition, an ion-fixing layer having the electric charge amplifying function or the like may also be laminated on the dielectric layer.

Hereinafter, an embodiment of the converter of the present invention will be explained. 1 shows a sectional schematic view of an actuator. As in 1 shown includes the actuator 1 a dielectric layer 10 , a pair of electrodes 11a . 11b , and wirings 12a . 12b , The dielectric layer 10 consists of a crosslinked body of a random copolymer of butyl acrylate (monomer A), cyanoethyl acrylate (monomer B) and acrylic acid (monomer C). The constitutional formula of the random copolymer is shown by the following formula (1).

The monomer B has a cyano group (-CN) as a polar group. The monomer C has as a functional group a carboxyl group (-COOH). As shown in the formula (1), in the constitutional unit consisting of the monomer B in the copolymer, the self-bonded carbon atom of the polar group (-CN) as the first atom is coupled to the polymer main chain through four straight-chain linked atoms (CCOC). The relative dielectric constant of the random copolymer is 15, and the elastic modulus is 0.8 MPa. The crosslinked body of the random copolymer is contained in the dielectric elastomeric material of the present invention. The actuator 1 is included in the converter of the present invention.

The electrode 11a is disposed so as to cover approximately the entire upper surface of the dielectric layer 10 covered. Likewise, the electrode 11b arranged so that it covers approximately the entire lower surface of the dielectric layer 10 covered. The electrodes 11a . 11b each contain acrylic rubber and carbon black. The electrodes 11a . 12b are each via a wiring 12a . 12b to the power source 13 connected.

If between the pair of electrodes 11a . 11b a voltage is applied, the thickness of the dielectric layer becomes 10 less and expands to that extent with respect to the surfaces of the electrodes 11a . 11b in the parallel direction. Thereby, a driving force is output in the vertical direction and in the left-right direction in the figure.

In the constituent unit of the copolymer consisting of the monomer B, which is the dielectric layer 10 forms four straight-chain atoms between the polar group and the polymer main chain. That is, the polar group and the polymer main chain are separated by a certain distance. Therefore, the polar group hardly interferes with the polymer chain and the movement of the polar group is scarcely restricted by the polymer chain. Since the monomers A, B and C are random copolymerized, constitutional units of the monomer B having the polar group hardly follow each other as compared with a copolymerization. This suppresses interference between the polar groups and makes the polar groups easily mobile. As a result, the softness of the copolymer becomes high. Since the peculiarity of the polar groups that the polarity is high is brought about in full, the relative dielectric constant of the copolymer becomes high. Consequently, the dielectric layer is 10 soft and the relative dielectric constant of the dielectric layer 10 high. This can be done by the actuator 1 a great force and a large amount of displacement are obtained. If the structure of the actuator 1 As a sensor, a sensor with a high sensitivity can be performed.

embodiments

Hereinafter, the present invention will be concretely explained by embodiments.

Preparation of the copolymer

Copolymer 1

First, 37.2 g (0.29 mol) of butyl acrylate as monomer A, 86.3 g (0.69 mol) of cyanoethyl acrylate as monomer B, and 1.4 g (0.02 mol) of acrylic acid as monomer C in a flask with three openings and dissolved in 200 ml of N, N-dimethylformamide. Nitrogen was then bubbled through for 30 minutes. Thereafter, with respect to the entire monomer composition, 0.1 mass% of azobisisobutyronitrile was added as a radical initiator and heated and refluxed in a nitrogen atmosphere at 65 ° C for 14 hours. After the completion of the reaction, reprecipitation and purification were carried out using methanol, and drying was performed at a reduced pressure to give the copolymer 1 was obtained. By analyzing the obtained copolymer with a nuclear magnetic resonance (NMR) device, it was confirmed that the copolymer 1 is a random copolymer having the structure shown in the above formula (1) (the same applies hereinafter also to the copolymers 2 and 3 ). The fact that a carboxyl group is present in the constituent unit consisting of the monomer C was confirmed by a neutralization titration using a 0.1N potassium hydroxide solution in methanol with a phenolphthalein solution as an indicator (the same applies hereinafter also to the copolymers 2 to 12 , and 18 to 21 ).

Copolymer 2

The copolymer 2 except for a change in the addition amount of the butyl acrylate to 25.6 g (0.20 mol) and the addition amount of the cyanoethyl acrylate to 97.6 g (0.78 mol) in the same manner as the copolymer 1 manufactured.

Copolymer 3

The copolymer 3 was added to 12.8 g (0.10 mol) and the addition amount of the cyanoethyl acrylate to 110.1 g (0.88 mol) in the same manner as the copolymer except for a change in addition amount of the butyl acrylate 1 manufactured.

Copolymer 4

The copolymer 4 was except for a change of the monomer A to 2-ethylhexyl acrylate in the same manner as the copolymer 1 manufactured. The loading amount of the 2-ethylhexyl acrylate was 53.4 g (0.29 mol). By analyzing the obtained copolymer with an NMR device, it was confirmed that the copolymer 4 is a random copolymer having the structure shown in the following formula (2) (the same applies hereinafter also to the copolymers 5 and 6 ).

Copolymer 5

The copolymer 5 except for a change in the addition amount of 2-ethylhexyl acrylate to 36.9 g (0.20 mol) and the addition amount of the cyanoethyl acrylate to 97.6 g (0.78 mol) in the same manner as the copolymer 1 manufactured.

Copolymer 6

The copolymer 6 except for a change in the addition amount of 2-ethylhexyl acrylate to 18.4 g (0.10 mol) and the addition amount of the cyanoethyl acrylate to 110.1 g (0.88 mol) in the same manner as the copolymer 1 manufactured.

Copolymer 7

The copolymer 7 was except for a change of the monomer A to octyl acrylate in the same manner as the copolymer 1 manufactured. The addition amount of the octyl acrylate was 53.4 g (0.29 mol). By analyzing the obtained copolymer with an NMR device, it was confirmed that the copolymer 7 is a random copolymer having the structure shown in the following formula (3) (the same applies hereinafter also to the copolymer 8th ).

Copolymer 8

The copolymer 8th except for a change in the addition amount of the octyl acrylate to 36.9 g (0.20 mol) and the addition amount of the cyanoethyl acrylate to 97.6 g (0.78 mol) in the same manner as the copolymer 7 manufactured.

Copolymer 9

The copolymer 9 was except for a change of the monomer A to ethylene acrylate in the same manner as the copolymer 1 manufactured. The addition amount of the ethylene acrylate was 29.0 g (0.29 mol). By analyzing the obtained copolymer with an NMR device, it was confirmed that the copolymer 9 is a random copolymer having the structure shown in the following formula (4).

Copolymer 10

First, DCEA was prepared as monomer B. 10.6 g (0.10 mol) of 2-methyleneglutaronitrile, 9.2 g (0.10 mol) of 3-mercapto-1-propanol, and 0.62 ml of diisopropylamine were placed in an eggplant-shaped flask and dissolved in 100 ml of methanol 6 Stirred for hours at room temperature. After the end of the reaction, drying was carried out at a reduced pressure, and then 100 ml of toluene, 7.2 g (0.10 mol) of acrylic acid, 0.5 g of p-toluenesulfonic acid and 0.01 g of hydroquinone were added, followed by 6 hours long a heating and a reflux. After the completion of the reaction, the organic phase was recovered by a separation operation using demineralized water, and drying was carried out at a reduced pressure to obtain DCEA having the structure shown by the following formula (5).

Subsequently, 97.6 g (0.78 mol) of cyanoethyl acrylate as monomer B and 50.5 g (0.20 mol) of DCEA as monomer B, and 1.4 g (0.02 mol) of acrylic acid as monomer C in a flask with three openings and dissolved in 200 ml of N, N-dimethylformamide. Nitrogen was then bubbled through for 30 minutes. Thereafter, with respect to the entire monomer composition, 0.1 mass% of azobisisobutyronitrile was added as a radical initiator and heated and refluxed in a nitrogen atmosphere at 65 ° C for 14 hours. After the completion of the reaction, reprecipitation and purification were carried out using methanol, and drying was performed at a reduced pressure to give the copolymer 10 was obtained. By analyzing the obtained copolymer with an NMR device, it was confirmed that the copolymer 10 is a random copolymer having the structure shown in the following formula (6).

Copolymer 11

First CEVE was prepared as monomer B. 8.8 g (0.10 mol) of ethylene glycol monovinyl ether and 5.3 g (0.10 mol) of acrylonitrile were placed in an eggplant-shaped flask and, after being dissolved in 100 ml of a 2M aqueous sodium hydroxide solution, stirred at room temperature for 6 hours. After the end of the reaction, the organic phase was recovered by a separation operation using dichloromethane and demineralized water, and drying was performed at a reduced pressure to obtain CEVE having the structure shown by the following formula (7).

Subsequently, 18.0 g (0.34 mol) of acrylonitrile as monomer B, 90.4 g (0.64 mol) CEVE as monomer B, and 1.4 g (0.02 mol) of acrylic acid as monomer C in a flask with three openings and dissolved in 200 ml of N, N-dimethylformamide. Nitrogen was then bubbled through for 30 minutes. Thereafter, with respect to the entire monomer composition, 0.1 mass% of azobisisobutyronitrile was added as a radical initiator and heated and refluxed in a nitrogen atmosphere at 65 ° C for 14 hours. After the completion of the reaction, reprecipitation and purification were carried out using methanol, and drying was performed at a reduced pressure to give the copolymer 11 was obtained. By analyzing the obtained copolymer with an NMR device, it was confirmed that the copolymer 11 is a random copolymer having the structure shown in the following formula (8).

Copolymer 12

The copolymer 12 was 122.6 g (0.98 mol) in the same manner as the copolymer except for not using the monomer A and changing the addition amount of the cyanoethyl acrylate 1 manufactured. By analyzing the obtained copolymer with an NMR device, it was confirmed that the copolymer 12 is a random copolymer having the structure shown in the following formula (9).

Copolymer 13

The copolymer 13 was added to 87.5 g (0.70 mol) in the same manner as the copolymer except for not using monomer C and changing the addition amount of the butyl acrylate to 38.5 g (0.30 mol) and the addition amount of the cyanoethyl acrylate 1 manufactured. By analyzing the obtained copolymer with an NMR device, it was confirmed that the copolymer 13 is a random copolymer having the structure shown in the following formula (10).

Copolymer 14

First, cyano group-modified silane 1 and cyano group-modified silane 2 prepared as monomer B.

Cyano group modified silane 1

5.3 g (0.10 mol) of acrylonitrile, 19.8 g (0.11 mol) of dimethoxy 3 -mercaptopropylmethylsilane and 0.62 ml of diisopropylamine were placed in an eggplant-shaped flask and dissolved in 100 ml of methanol 6 Stirred for hours at room temperature. After the end of the reaction, drying at one reduced pressure, thereby reducing the cyano group-modified silane 1 having the structure shown in the following formula (11).

Cyano group modified silane 2

10.6 g (0.10 mol) of 2-methylene glutaronitrile, 19.8 g (0.11 mol) of dimethoxy-3-mercaptopropylmethylsilane and 0.62 ml of diisopropylamine were placed in an eggplant-shaped flask and dissolved in 100 ml of methanol 6 Stirred for hours at room temperature. After the end of the reaction was a drying made at a reduced pressure, whereby the cyano group-modified silane 2 having the structure shown in the following formula (12).

Next, the copolymer was prepared without using the monomer C of the monomer A and the monomer B. First, 40.9 g (0.34 mol) of diethoxydimethylsilane as monomer A and 77.0 g (0.33 mol) of the cyan-modified silane 1 and 94 , 5 g (0.33 mol) of the cyan-modified silane 2 as monomer B in an eggplant-shaped flask and at room temperature 1 Stirred for an hour. Subsequently, with respect to the entire monomer mass 10 Added mass% dibutyltin diacetate as a catalyst and heated under atmospheric pressure at 110 ° C for 6 hours and stirred. After the completion of the reaction, reprecipitation and purification were carried out using methanol, and drying was performed at a reduced pressure to give the copolymer 14 (Silane group-modified silicone rubber) was obtained. By analyzing the obtained copolymer with an NMR device, it was confirmed that the copolymer 14 is a random copolymer having the structure shown in the above formula (13). Here, diethoxymethylsilane was used as the monomer A. However, diethoxymethylsilane has a silanol group, which is a crosslinkable functional group. Therefore, diethoxymethylsilane can also be used as monomer C (the same applies in the following for the copolymers 15 to 17 ).

Copolymer 15

The copolymer 15 except for use of 189.1 g (0.66 mole) of cyano group-modified silane 2 as monomer B in the same manner as the copolymer 14 manufactured. By analyzing the obtained copolymer with an NMR device, it was confirmed that the copolymer 15 is a random copolymer having the structure shown in the following formula (14).

Copolymer 16

First, carbonate group-modified silane was prepared as monomer B. 11.4 g (0.10 mol) of vinyl ethylene carbonate, 19.8 g (0.11 mol) of dimethoxy-3-mercaptopropylmethylsilane and 0.62 ml of diisopropylamine were placed in an eggplant-shaped flask and dissolved in 100 ml of methanol at room temperature 6 Stirred for hours. After the end of the reaction, drying was carried out at a reduced pressure to obtain carbonate group-modified silane having the structure shown in the following formula (15).

Next, the copolymer became 16 with the exception of using only 194.3 g (0.66 mol) of the carbonate group-modified silane as monomer B in the same manner as the copolymer 14 manufactured. By analyzing the obtained copolymer with an NMR device, it was confirmed that the copolymer 16 is a random copolymer having the structure shown in the following formula (16).

Copolymer 17

The copolymer 17 except for use of 94.5 g (0.33 mol) of the cyano group-modified silane 2 and 97 , 2 g (0.33 mol) of the carbonate group-modified silane as monomer B in the same manner as the copolymer 14 manufactured. By analyzing the obtained copolymer with an NMR device, it was confirmed that the copolymer 17 is a random copolymer having the structure shown in the following formula (17).

Copolymer 18

First, after dissolving 1.25 g of carboxyl-containing NBR ("XER-32" from JSR KK) in 100 ml of tetrahydrofuran (THF), 18.4 ml of a 0.5 M THF solution of 9-borabicyclo [3.3 .1] nonane (9-BBN) and 0.95 g of 5-chlorovaleronitrile were added and stirred for 0.5 hours. Subsequently, in a water bath, 1.90 g of potassium 2,6-di-tert-butylphenol was added and stirred for 2 hours. After the completion of the reaction, reprecipitation and purification were carried out using methanol, and drying was performed at a reduced pressure to give the copolymer 18 (cyano group-modified NBR) was obtained. By analyzing the obtained copolymer with an NMR device, it was confirmed that the copolymer 18 is a random copolymer having the structure shown in the following formula (18).

Copolymer 19

First, 88.4 g (0.69 mol) of butyl acrylate as monomer A, 15.4 g (0.29 mol) of acrylonitrile as a monomer having a polar group, and 1.4 g (0.02 mol) of acrylic acid as monomer C were used placed in a three-necked flask and bubbled with nitrogen for 30 minutes. Then, with respect to the whole monomer composition, 0.1 mass% of azobisisobutyronitrile was added as a radical initiator, and heating and refluxing were conducted in a nitrogen atmosphere at 65 ° C for 3 hours. After the completion of the reaction, reprecipitation and purification were carried out using methanol, and drying was performed at a reduced pressure to give the copolymer 19 was obtained. By analyzing the obtained copolymer with an NMR device, it was confirmed that the copolymer 19 is a random copolymer having the structure shown in the following formula (19) (the same applies hereinafter also to the copolymers 20 and 21 ).

Copolymer 20

The copolymer 20 was added to 69.2 g (0.54 mol) and the addition amount of acrylonitrile to 23.3 g (0.44 mol) in the same manner as the copolymer except for a change in the addition amount of the butyl acrylate 19 manufactured.

Copolymer 21

The copolymer 21 was added to 62.8 g (0.49 mol) and the addition amount of the acrylonitrile to 26.0 g (0.49 mol) in the same manner as the copolymer except for a change in the addition amount of the butyl acrylate 19 manufactured.

Measurement of the material properties of the copolymers

The weight-average molecular weight of the prepared copolymers was measured by using a GPC apparatus, and the glass transition point was measured by using DSC. In addition, samples prepared as follows for the measurement of the relative dielectric constants, the volume resistivity and the modulus of elasticity of the copolymers were used for the measurement. First, the copolymers were dissolved in acetylacetone and prepared polymer solutions having a solids content concentration of 20% by mass. Then, the prepared polymer solutions were coated on substrates and dried, followed by heating at 150 ° C for 60 minutes to obtain thin film samples for measurement.

The relative dielectric constant

The relative dielectric constant was measured as described above using a Solartron device at a frequency of 100 Hz.

The volume resistance

The volume resistivity was measured according to the parallel clamp method determined in JIS K6271: 2008. The measurement was made applying a DC voltage of 100V.

The modulus of elasticity

Young's modulus was measured according to the method of static shear modulus determined in JIS K6254: 2010. For the measurement was a strip-shaped test piece with the shape 1 used, wherein the tensile speed in the tensile test 100 mm / min and the tensile elongation was 25%.

Table 1 and Table 2 summarize the composition and the material properties of the copolymers. The copolymers 1 to 18 are contained in the copolymer constituting the dielectric elastomer material of the present invention. For comparison, the physical properties of commercial acrylic rubber ("Nipol" registered trademark) AR53L from Zeon Corporation), silicone rubber ("KE-1935" from Shin-Etsu Chemical Co., Ltd.), and carboxyl group-containing NBR ("XER") are also included. 32 "from the JSR KK).

Now if the materials with the same base polymers as in the embodiments 1 to 13 and the comparative forms 1 to 4 , the embodiments 14 to 17 and the comparative form 5 , and the embodiment 18 and the comparative form 6 are compared with each other, the relative dielectric constant of the embodiments is higher than those of the comparative forms, respectively. The main difference between the embodiments 1 to 13 (copolymers 1 to 13 ) and the comparison forms 1 to 3 (copolymers 19 to 21 ) is the type of monomer B. In the comparative forms 1 to 3 was used as monomer B acrylonitrile. In this case, in the constitutional units of the monomer B, the copolymers 19 to 21 the cyano groups are coupled directly to the carbon of the polymer backbone. That is, there is not an atom between the cyano groups and the polymer backbone. Therefore, it can be assumed that the cyano groups interfere with the polymer chain and the properties as polar groups can hardly be brought about.

If now the copolymers 1 to 3 . 4 to 6 . 7 and 8th According to the embodiments, it was confirmed that the relative dielectric constant and Young's modulus of the same kind of the monomer B become larger as the amount of addition thereof increases. In contrast, in the case of the copolymers 19 to 21 In comparison, when the addition amount of the monomer B was increased and the polar group content was increased, the modulus of elasticity became larger, but the relative dielectric constant did not increase. Again, the reason is assumed that the cyano groups are coupled directly to the carbon of the polymer main chain and the cyano groups therefore interfere with the polymer chain and the properties as polar groups can hardly be brought about.

The copolymers 10 to 17 of the embodiments are binary copolymers of monomers B and C or monomers A and B. Also for these copolymers, as for the tertiary copolymers of monomers A, B and C, an effect of increasing the relative dielectric constant was observed.

Actuator properties 1

Using the copolymers 1 . 2 . 11 . 14 and 19 For example, dielectric layers were fabricated and electrostrictive type actuators comprising these dielectric layers were fabricated. First, the copolymer was dissolved in acetylacetone, and a polymer solution having a solid content concentration of 20% by mass was prepared. Subsequently, 5 parts by mass of an acetone solution of tetrakis (2-ethylhexyloxy) titanium (concentration: 20% by mass) as a crosslinking agent and 12.42 parts by mass of titanium oxide particles as an electrically insulating filler were added with respect to 100 parts by mass of the polymer solution, thereby preparing a mixed solution. The prepared mixed solution was coated on a substrate and dried, followed by heating at 150 ° C for 60 minutes to prepare a thin-film dielectric layer having a thickness of 10 μm. Separated therefrom were 100 parts by weight of an acrylic rubber polymer solution 10 Carbon black, thereby producing a conductive coating material. The prepared conductive coating material was coated on substrates and dried, followed by heating at 150 ° C for 60 minutes to prepare thin-film dielectric electrodes having a thickness of 5 μm. The volume resistivity of the electrodes was 5 Ω · cm. The fabricated electrodes were bonded to the front and back surfaces in the thickness direction of the dielectric layer, thereby forming a pair of electrodes. In this way four types of actuators with different dielectric layers were produced. The copolymers 1 . 2 . 11 and 14 are contained in the copolymer constituting the dielectric elastomer material of the present invention. The actuators of the embodiments 1 . 2 . 11 and 14 made from the copolymers 1 . 2 . 11 and 14 prepared dielectric layers are included in the transducer of the present invention. In addition, a dielectric layer was formed from the above-mentioned commercial acrylic rubber and an electrode was formed in the same manner on the front and back surfaces in the thickness direction of the dielectric layer, thereby producing an actuator. Then, a measurement was made of the dielectric breakdown strength, the generated force and the amount of displacement for the individual actuators.

First, the measuring apparatus and method for measuring dielectric breakdown strength will be explained. 2 Fig. 10 is a front front view of the actuator attached to the measuring device. 3 shows a sectional view along III-III in 2 ,

As in 2 and 3 shown is an upper end of the actuator 5 through an upper clamping device 52 held the measuring device. The lower end of the actuator 5 is through a lower chuck 53 held. The actuator 5 is in a pre-stretched in the vertical direction state between the upper chuck 52 and the lower chuck 53 attached (elongation rate: 25%). Above the upper clamping device, a load cell (not shown) is arranged.

The actuator 5 consists of a dielectric layer 50 and a pair of electrodes 51a . 51b , The dielectric layer 50 shows in its natural state a rectangular plate shape with a length of 50 mm and a width of 25 mm. The electrodes 51a . 51b are arranged so that they face each other with the dielectric layer 50 between them in the front-rear direction. The electrodes 51a . 51b each show a rectangular plate shape in the natural state with a length of 40 mm, a width of 25 mm and a thickness of about 10 microns. The electrodes 51a . 51b are arranged in the vertical direction in a state offset by 10 mm. That is, the electrodes 51a . 51b overlap each other via the dielectric layer 50 in an area with a length of 30 mm and a width of 25 mm. To the lower end of the electrode 51a a wiring (not shown) is connected. Likewise, to the top of the electrode 51b a wiring (not shown) connected. The electrodes 51a . 51b are connected via the respective wiring to a power source (not shown).

The measurement of the dielectric breakdown strength was accompanied by a stepwise increase between the electrodes 51a . 51b applied voltage until breakage of the dielectric layer 50 performed. Then, a value for which the voltage value immediately before the breakage of the dielectric layer became 50 through the thickness of the dielectric layer 50 was divided, as dielectric dielectric strength set.

Next, the measuring apparatus and method for measuring the generated force will be explained. The measurement of the generated force was made using the same device as in the measurement of the dielectric breakdown strength (see 2 and 3 ). If between the electrodes 51a . 51b a voltage is applied arises between the electrodes 51a . 51b an electrostatic attraction and attracts the dielectric layer 50 together. This will increase the thickness of the dielectric layer 50 thinner and expands in the stretching direction (the vertical direction). By the extension of the dielectric layer 50 decreases the stretching force in the vertical direction. The strain force decreasing upon application of a stress was measured by the load cell and applied as generated force. The measurement of the generated force was made by setting the electric field strength to 30 V / μm. Next, the measuring apparatus and method for measuring the amount of displacement will be explained. 4 shows a plan view of an actuator. 5 shows a sectional view along VV in 4 , As in 4 and 5 shown, consists of the actuator 6 from a dielectric layer 60 and a pair of electrodes 61a . 61b , The dielectric layer 60 shows a round thin-film mold with a diameter of 70 mm. The dielectric layer 60 is arranged in a longitudinal and transverse biaxial stretched by 25% state. The pair of electrodes 61a . 61b is arranged so that it is one another with the dielectric layer 60 therebetween in the thickness direction. The electrodes 61a . 61b show a round thin-film shape with a diameter of about 27 mm and are each approximately concentric with the dielectric layer 60 arranged. At the outer peripheral edge of the electrode 61a is a clamping portion projecting in the radial direction 610a educated. The terminal section 610a shows a rectangular plate shape. Likewise, on the outer peripheral edge of the electrode 61b a clamping portion projecting in the radial direction 610b educated. The terminal section 610b shows a rectangular plate shape. The terminal section 610b is with respect to the terminal section 610a arranged at a position opposite by 180 °. The terminal sections 610a . 610b are each via a lead wire to a power source 62 connected.

If between the electrodes 61a . 61b a voltage is applied arises between the electrodes 61a . 61b an electrostatic attraction and attracts the dielectric layer 60 together. This will increase the thickness of the dielectric layer 60 thinner and expands in the radial direction. The electrodes also stretch 61a . 61b integral with the dielectric layer 60 in the radial direction. At the electrode 61a was a mark in advance 630 appropriate. The shift of the mark 630 was through a displacement meter 63 measured and as a shift amount of the actuator 6 stated. The measurement of the shift amount was made by setting the electric field intensity at 30 V / μm. Then, from the measured shift amount by the following formula (ii), a shift rate was calculated. $$\begin{array}{l}\text{displacement rate}\left(\text{\%}\right)=\left(\text{Displacement amount / radius of the electrode}\right)\\ \times 100\end{array}$$

The measurement results of the generated force, the displacement rate and the dielectric strength of the individual actuators are shown in Table 3 and Table 4.

As described above, the copolymers are different 1 . 2 and the copolymer 19 the type of monomer B, and is the relative dielectric constant in the copolymers 1 . 2 greater. As a result, as shown in Table 3 and Table 4, in the actuators of Embodiment 1 and 2 made from the copolymers 1 and 2 prepared dielectric layers include, the generated force and the displacement rate larger than in the actuator of the comparative form 1 , one from the copolymer 19 prepared dielectric layer comprises. In addition, in the actuators of the embodiments 1 . 2 . 11 and 14 the force generated and the displacement rate compared to the comparison forms 4 and 5 larger, comprising a dielectric layer made of acrylic rubber or silicone rubber.

Actuator properties 2

Using the copolymers 1 and 11 For example, dielectric layers were fabricated, and electrostrictive type actuators comprising these dielectric layers were fabricated. The structure of the manufactured actuators was the same as that of the "actuator characteristics 1" except for the fact that an ion-fixing layer was layered on the front and rear surfaces in the thickness direction of the dielectric layer. That is, in the manufactured actuators, the electrodes are disposed on the front and back surfaces of a laminated body of a cation fixing layer, a dielectric layer, and an anion fixing layer. The methods for producing the dielectric layer and the electrodes were the same as those of the "actuator characteristics 1". Hereinafter, the anion fixing layer and the cation fixing layer (ion fixing layers) will be explained.

The anion fixation layer

First, a reactive ionic liquid was prepared. In 5.0 g of a solution of 1-butyl-3-methylimidazolium hydrogencarbonate (solvent: mixed solution of methanol / water = 3: 2, concentration 50 Dimensions-%; 0.0125 mol), an acrylic acid monomer in the same molar amount (on an ice bath) ( 0 , 0125 mol) is added dropwise. It was checked that air bubbles escape. To 30 For a few minutes, it returned to room temperature and was stirred for 6 hours. After removing the solvent at a reduced pressure, methanol (extremely dehydrated) (from Wako Pure Chemicals Co., Ltd.) was added and the solvent was again removed at a reduced pressure. In this way, an ionic liquid monomer was obtained. 2.10 g (10.0 mmol) of the obtained ionic liquid monomer and 1.87 ml (10.1 mmol) of 3-mercaptopropyltrimethoxysilane were dissolved in 20 ml of methanol (extremely dehydrated). With respect to the 3-mercaptopropyltrimethoxysilane, 10 mol% of diisopropylamine was added as a catalyst at room temperature 20 Stirred for hours, and the solvent was eliminated at a reduced pressure, whereby the reactive ionic liquid shown by the following formula (20) was obtained.

Next, the anion fixation layer was prepared. The prepared reactive ionic liquid was dissolved in a mixed liquid for which titanium tetraisopropoxide and acetylacetone were mixed in a molar ratio of 1: 1. To this mixed liquid was added isopropyl alcohol (IPA) and further added dropwise water in four times the number of moles of the titanium tetraisopropoxide, and a hydrolysis reaction was carried out. Thus, a sol containing TiO ₂ particles to which the anionic component of the reactive ionic liquid was fixed and the cationic component of the reactive ionic liquid were obtained. The resulting sol was mixed with a 12% by mass solution of carboxyl group-modified nitrile rubber, (HX-NBR, "Therban (registered trademark) XT8889", from Lanxess KK) (solvent: acetylacetone). The sol was mixed so as to contain 2.4 parts by mass with respect to 100 parts by mass of HX-NBR in TiO ₂ . To the mixed liquid in which the sol was mixed, 5 parts by mass of an acetylacetone solution of tetrakis (2-ethylhexyloxy) titanium (concentration: 20% by mass) as a crosslinking agent was added to obtain an elastomer composition in a liquid state. The elastomer composition was coated on a substrate and heated after drying at 150 ° C for one hour to obtain the anion-fixing layer. The thickness of the anion-fixing layer was 10 μm.

The cation fixation layer

First, a reactive ionic liquid was prepared. In 16.2 g of a solution of 1-methyl-3-vinylimidazoliummethyl carbonate salt (solvent: mixed solution of methanol / water = 3: 2, concentration 25% by mass, 0.022 mol) 3.80 benzenesulfonic acid monohydrate in the same molar amount (0.022 Mol) dripped. After stirring at room temperature for 1 hour, the solvent was removed at a reduced pressure and dried at a reduced pressure for 2 hours. In this way, an ionic liquid monomer was obtained. 3.00 g (11.3 mmol) of the obtained ionic liquid monomer and 2.43 g (12.4 mmol) of 3-mercaptotrimethoxysilane were dissolved in 40 ml of methanol (extremely dehydrated). With respect to the 3-mercyptotrimethoxysilane, 15 mol% of azobisisobutyronitrile was added as a radical generator, and after bubbling argon for 30 minutes, a reflux of seven hours was carried out at a temperature of 75 ° C under argon. After removing the solvent at a reduced pressure and purifying with diethyl ether, drying was carried out at a reduced pressure to obtain the reactive ionic liquid shown by the following formula (21).

Subsequently, the cation fixing layer was prepared. The produced reactive ionic liquid was dissolved in a mixed solution for which titanium tetraisopropoxide and acetylacetone were mixed in a molar ratio of 1: 1. This mixed liquid was added with IPA and further added dropwise water in four times the number of moles of the titanium tetraisopropoxide, and a hydrolysis reaction was carried out. Thus, a sol containing TiO ₂ particles to which the cationic component of the reactive ionic liquid was fixed and the anionic component of the reactive ionic liquid was obtained. The resulting sol was mixed with a 12% by mass solution of HX-NBR (as above) (solvent: acetylacetone). The sol was mixed so as to contain 2.4 parts by mass with respect to 100 parts by mass of HX-NBR in TiO ₂ . To the mixed liquid in which the sol was mixed, 5 parts by mass of an acetylacetone solution of tetrakis (2-ethylhexyloxy) titanium (concentration: 20% by mass) as a crosslinking agent was added to obtain an elastomer composition in a liquid state. The elastomer composition was coated on a substrate and heated after drying at 150 ° C for one hour to obtain the cation fixing layer. The thickness of the cation fixing layer was 10 μm.

The cation fixing layer was bonded to the front surface of a dielectric layer and the anion fixing layer to its back surface, and by peeling the substrate respectively, a laminate having a three-layered structure was prepared. By bonding electrodes to the front and back surfaces of the produced composite, an actuator was produced. The actuators of the embodiments 1 and 11 made from the copolymers 1 and 11 prepared dielectric layers are included in the transducer of the present invention. For the respective actuators were the dielectric Dielectric strength, the force generated and the amount of displacement measured in the same manner as in "actuator properties 1".

In the above Table 3, the generated force, the displacement rate and the dielectric breakdown strength of the individual actuators are indicated. As shown in Table 3, the generated force, the shift rate and the dielectric breakdown strength are made by coating ion-fixing layers on those of the copolymers 1 and 11 produced dielectric layers greatly increased.

The sensor properties

Using the copolymers 1 to 21 For example, dielectric layers were fabricated and capacitive type sensors comprising these dielectric layers were fabricated. First, the copolymer was dissolved in acetylacetone, and a polymer solution having a solid content concentration of 20% by mass was prepared. Subsequently, 5 parts by mass of an acetone solution of tetrakis (2-ethylhexyloxy) titanium (concentration: 20% by mass) as a crosslinking agent was added relative to 100 parts by mass of the polymer solution, thereby preparing a mixed solution. The prepared mixed solution was coated on a substrate and dried, followed by heating at 150 ° C for 60 minutes to prepare a thin-film dielectric layer having a thickness of 10 μm. Separated therefrom were 100 parts by weight of an acrylic rubber polymer solution 10 Carbon black, thereby producing a conductive coating material. The prepared conductive coating material was coated on substrates and dried, followed by heating at 150 ° C for 60 minutes to prepare thin-film dielectric electrodes having a thickness of 5 μm. The volume resistivity of the electrodes was 5 Ω · cm. The fabricated electrodes were bonded to the front and back surfaces in the thickness direction of the dielectric layer, thereby forming a pair of electrodes. In this way, fifteen kinds of sensors were manufactured. The copolymers 1 to 18 are contained in the copolymer constituting the dielectric elastomer material of the present invention. The sensors of the embodiments 1 to 18 made from the copolymers 1 to 18 prepared dielectric layers are included in the transducer of the present invention. In addition, dielectric layers were also prepared from the above-mentioned commercial acrylic rubber, silicone rubber, and carboxyl group-containing NBR and adhered to the front and back surfaces in the thickness direction of the dielectric layers in the same manner as above, thereby producing sensors.

For the sensors produced, the initial capacity (when not expanded) was measured first. Then, the sensor was stretched in one direction of the surface direction, and the capacity was measured at an elongation of 100%. Then, the initial capacity was subtracted from the capacity in the expansion and the amount of change of the capacity was calculated. Capacity was measured using an LCR meter ("E4980AL" from Keysight Technologies).

In Table 3 and Table 4, the measurement results of the initial capacity and that of the strain and the amount of change of the capacity are shown. As shown in Table 3 and Table 4, when comparing the sensors with the same base polymers as in the embodiments 1 to 13 and the comparative forms 1 to 4 , the embodiments 14 to 17 and the comparative form 5 , and the embodiment 18 and the comparative form 6 the capacitances and the amount of change in capacitance are greater in the sensors of the embodiments than in the sensors of the comparative forms. In the sensor of the embodiment 12 Although the amount of change of the capacity was slightly lower than that of the sensor of the comparative form 1 , but it was compared with the sensors of the comparison forms 2 to 4 greater. The larger the amount of change of the capacitance, the higher the sensitivity becomes, and the smaller shifts can be detected.

Commercial application

The transducer of the present invention can be widely used as a transducer, sensor or power generating element, or the like, that converts mechanical energy into electrical energy, or as a speaker, microphone, noise suppressor, or the like that converts sound energy into electrical energy , Above all, as a soft actuator used for artificial muscles used in industrial, medical or care robots or the like, for small-sized pumps for cooling electronic components or medical purposes, or the like, it is sensitive to vibration (haptic) ) Items, as well as medical equipment, or the like is used ideally. In addition, it is ideal as a portable sensor for biological information or as a pressure sensor placed in artificial skin of robots, mattresses for medical or nursing purposes, seats of wheelchairs, or the like.

Claims (12)

A dielectric elastomeric material characterized by randomly or alternately copolymerizing a copolymer having a structure of which at least one of a monomer A and a monomer C having a crosslinkable functional group and a monomer B having a polar group is copolymerized, wherein, in the copolymer, the polar group in the constituent units consisting of the monomer B is coupled to the polymer main chain via at least three straight-chain connected atoms. Dielectric elastomer material after Claim 1 wherein the amount of polar groups contained when the total copolymer is used as 100% by mass is at least 10% by mass and at most 25% by mass. Dielectric elastomer material after Claim 1 or Claim 2 wherein the amount of the monomer B contained when the total copolymer is used as 100 mol% is at least 50 mol% and at most 98 mol%. Dielectric elastomer material according to one of Claims 1 to 3 wherein the atoms present between the polar group and the polymer backbone are at least one of carbon, oxygen, nitrogen and sulfur. Dielectric elastomer material according to one of Claims 1 to 4 wherein the polar group is at least one kind selected from a cyano group, an ether group, an ester group, a fluoro group, a trifluoromethyl group and a carbonate group. Dielectric elastomer material according to one of Claims 1 to 5 wherein the weight average molecular weight of the copolymer is at least 10,000 and at most 5,000,000. Dielectric elastomer material according to one of Claims 1 to 6 wherein the glass transition point of the copolymer is at most 0 ° C. Dielectric elastomer material according to one of Claims 1 to 7 wherein the functional group of the monomer C is at least one kind selected from a hydroxy group, an amino group, a thiol group, a carboxyl group, a silanol group, an epoxy group and a vinyl group. Dielectric elastomer material according to one of Claims 1 to 8th wherein the monomer A is at least one kind selected from (meth) acrylate monomers, silicone monomers and urethane monomers. Dielectric elastomer material according to one of Claims 1 to 9 , further comprising an insulating filler. Dielectric elastomer material according to one of Claims 1 to 10 wherein the copolymer has a crosslinked structure. Transducer, characterized in that it comprises one of the dielectric elastomeric material according to any one of Claims 1 to 11 formed dielectric layer and a plurality of arranged electrodes, with the dielectric layer inserted between the electrodes comprises.

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